Recommended Posts

Gday guys

Ok car was idling fine before i changed the fuel pump now it is stalling or idling very rough but drives fine all i done is put a new fuel pump on it what could it be 

Thanks 

Share this post


Link to post
Share on other sites
Members dont see this ad

Probably disturbed a bit of dirt that has got stuck in the carb idle circuit..  or maybe the new pump is more efficient and running it rich.


Can you tune it out with idle mixture and idle  speed??

Share this post


Link to post
Share on other sites

I'm assuming this is new mechanical fuel pump, fitted to a K Series engine ?

image.png.8252728b778246b4ca396ca180d7ddce.png

The first thing to check is what volume the pump is delivering.  Remove all spark plugs.  Disconnect metal fuel line at the carby.  Run a hose from this fuel line into a container, & turn the engine over for 10-15 seconds.  Measure how much fuel is collected. 

You may have disturbed something, during the changeover.  The smallest crack on the suction side of the pump, in a rubber hose, can cause horrible delivery issues.

Did you refit the stand-off "gasket shaped" mounting block, between pump & engine ?

Let us know how you go.

Cheers Banjo

 

 

 

Edited by Banjo

Share this post


Link to post
Share on other sites
21 hours ago, Banjo said:

I'm assuming this is new mechanical fuel pump, fitted to a K Series engine ?

image.png.8252728b778246b4ca396ca180d7ddce.png

The first thing to check is what volume the pump is delivering.  Remove all spark plugs.  Disconnect metal fuel line at the carby.  Run a hose from this fuel line into a container, & turn the engine over for 10-15 seconds.  Measure how much fuel is collected. 

You may have disturbed something, during the changeover.  The smallest crack on the suction side of the pump, in a rubber hose, can cause horrible delivery issues.

Did you refit the stand-off "gasket shaped" mounting block, between pump & engine ?

Let us know how you go.

Cheers Banjo

 

 

 

My pump has a return on it 

Why does it come with 2 gaskets and if it was a fuel delivery problem wouldn't it drive terrible as well 

Share this post


Link to post
Share on other sites

There's a carb picture here-

https://www.rollaclub.com/board/topic/68402-setting-mixer-and-idle-in-ke70/

Basically get the fastest idle speed with the mixture screw by screwing it in and out, then set the actual idle speed with the idle speed screw. It should slow down when you screw the mixture too far in, or too far out. Try half-turns first, then fine it down with 1/4 turns.

Make sure the cold idle screw doesn't touch the throttle quandrant when the choke is in, it should just hold the throttle open when the choke is pulled out. It shouldn't need touching once set by the factory.

The two gaskets go one on each side of the plastic insulator, between the pump and the block. Its stops the pump absorbing engine heat and vaporising the fuel.

Share this post


Link to post
Share on other sites

The two gaskets are supplied, as they are both needed.

1. One gasket fits between the engine block & the mounting spacer.

2. The second gasket fits between the mounting block & the fuel pump flange.

You probably only fitted one, because you did no remove the mounting spacer, from the the engine block.

The spacer is that dark bit in the picture below.

It stops the fuel pump getting too hot, & vaporising the fuel.

171206123_FuelPumpmountingblock.jpg.e6de0dc034122a6d92bd2e9a434da105.jpg

Cheers Banjo

 

Edited by Banjo

Share this post


Link to post
Share on other sites
Quote

I tried playing with the screw but not if it was the right screw it didn't change anything tho i can only see 2 screws is there a third 

This is the idle adjustment screw.  It has a spring behind it.

4K-Engine-Carburetor-New-For-Toyota-Corolla-Ke70.jpg.b8d699def2cdec437de9ba9d5398bd69.jpg

Hope that assists.

Cheers Banjo

 

Edited by Banjo

Share this post


Link to post
Share on other sites
9 minutes ago, Banjo said:

This is the idle adjustment screw.  It has a spring behind it.

4K-Engine-Carburetor-New-For-Toyota-Corolla-Ke70.jpg.b8d699def2cdec437de9ba9d5398bd69.jpg

Hope that assists.

Cheers Banjo

 

Which screw is the mixture screw 

Share this post


Link to post
Share on other sites
Quote

Which screw is the mixture screw 

That is the idling mixture adjustment screw, i've highlighted.  If you screw it right out, you'll see it has a "pointed" tip.

The idle speed adjustment is the big thumb screw to the right & up, in that picture.  It usually has a large screwdriver slot in it.

Cheers Banjo 

Share this post


Link to post
Share on other sites
8 hours ago, Banjo said:

That is the idling mixture adjustment screw, i've highlighted.  If you screw it right out, you'll see it has a "pointed" tip.

The idle speed adjustment is the big thumb screw to the right & up, in that picture.  It usually has a large screwdriver slot in it.

Cheers Banjo 

Cheers mate that worked good idle is sweet i had to wined it out does that mean it was lean 

Share this post


Link to post
Share on other sites
Quote

 i had to wined it out does that mean it was lean 

Yes !  When the idle mixture adjustment screw is wound in as far as it can go, it completely blocks fuel coming out the "idle port hole" at the very bottom of the primary venturi. As you unwind it, it allows more fuel to be sucked out of the idle port, & renders the idling mixture less lean.

A very good check is to make sure that the electric solenoid valve on the carby is working. It is powered by the ignition circuit.  It prevents run-on, once the ignition has been turned off, as it allows fuel to flow to the "slow" & "idle" ports only.

Once you have the idling good, & to your liking, simply disconnect the wire to the carby solenoid, & the engine should starve & stop, or at least get very fluffy.  That proves the solenoid is working

You can usually hear the solenoid clicking, if you turn the ignition switch on & off. 

Surprisingly, the idle circuit it still in play, & contributing to the overall A/F ratio, when you are driving.  I learnt this once on a long trip. All of sudden, the engine was not  "as strong", & I didn't know why. At the next small town I passed through, I had to pull up, at a pedestrian crossing, & the engine cut out.   That gave me the clue.

I pulled over, & found the green connector, for the single wire to the carby solenoid had gone o/c.  Cleaned it up, & it then idled properly, & the engine was back to full power.

Cheers Banjo

 

 

Share this post


Link to post
Share on other sites
29 minutes ago, Banjo said:

Yes !  When the idle mixture adjustment screw is wound in as far as it can go, it completely blocks fuel coming out the "idle port hole" at the very bottom of the primary venturi. As you unwind it, it allows more fuel to be sucked out of the idle port, & renders the idling mixture less lean.

A very good check is to make sure that the electric solenoid valve on the carby is working. It is powered by the ignition circuit.  It prevents run-on, once the ignition has been turned off, as it allows fuel to flow to the "slow" & "idle" ports only.

Once you have the idling good, & to your liking, simply disconnect the wire to the carby solenoid, & the engine should starve & stop, or at least get very fluffy.  That proves the solenoid is working

You can usually hear the solenoid clicking, if you turn the ignition switch on & off. 

Surprisingly, the idle circuit it still in play, & contributing to the overall A/F ratio, when you are driving.  I learnt this once on a long trip. All of sudden, the engine was not  "as strong", & I didn't know why. At the next small town I passed through, I had to pull up, at a pedestrian crossing, & the engine cut out.   That gave me the clue.

I pulled over, & found the green connector, for the single wire to the carby solenoid had gone o/c.  Cleaned it up, & it then idled properly, & the engine was back to full power.

Cheers

Yeh i unplugged that the other day when it started idling crap and the engine cut out so i knew that was a solenoid. So does this mean my new fuel pump has less fuel pressure or doesn't fuel pressure effect idle mixture 

Share this post


Link to post
Share on other sites
Quote

So does this mean my new fuel pump has less fuel pressure or doesn't fuel pressure effect idle mixture 

In theory, the fuel pressure, which is quite low, in the order of 4-10 PSI, has a slight effect, as higher pressure can allow the float cut-off needle, to only close when the fuel level in the bowl is a bit higher.  As your fuel pump has a return or bypass outlet, it should be pretty constant.

I wouldn't worry too much, as your engine's idling & driving performance, are to your satisfaction.

Carbies as old as ours, suffer from a build up of "fuel gum" & lacquers, in the tiny passages internally.

A good idea, is to dissemble the carby completely, & soak in a carby cleaning fluid, & then reassemble.   Not really recommended, unless you really know what you are doing.

A quick fix, is to remove the air cleaner, & give the carby a good dousing of carby & thottle cleaner, in a spray can.  Sometimes running the engine at 2000 rpm with the air cleaner off, & spraying thottle & carby cleaner straight into the throats, can often, get rid of annoying stumbles in the carby's performance.

Cheers Banjo

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now